LONDON (Reuters) - Olympic champion Lin Dan opened his badminton title defence in style at the London Games on Monday, but top seed Lee Chong Wei survived a huge scare in his opening match.

China's Lin Dan plays against Ireland's Scott Evans during their men's singles group play stage Group P badminton match during the London 2012 Olympic Games at the Wembley Arena July 30, 2012. REUTERS/Bazuki Muhammad

Malaysia's Lee went into his clash with world number 45 Ville Lang of Finland thoroughly under-done, having not played a competitive match since sustaining an ankle injury in May. After wrapping up the first set comfortably, Lee promptly fell in a hole in the second before closing out the match 21-8 14-21 21-11 with a series of smashes.

"(In the last part) I just tried my original Lee Chong Wei," he told reporters, appearing a little shell-shocked.

"Only mentally am I very, very strong. I'm still not 100 percent (physically) but I still beat him and can keep going on in the tournament."

Lee faces another stiff challenge in the last 16 where he will face Indonesian ninth seed Simon Santoso, but may not have bargained for such a torrid time against Lang, who played an inspired match after spotting Finland president Sauli Niinisto in the crowd.

"That was spectacular for me. I have never played before such a prestigious audience," Lang said after the Wembley Arena crowd got right behind him.

"I saw (the president) come in the match and thought, 'what am I going to do now? I need to play well." Lee's long-time nemesis Lin Dan, the man who beat him for both the world title at Wembley Arena last year and for gold at the Beijing Games, had a far easier time against Irishman Scott Evans, riding out a 21-8 21-14 winner.

"Today was pretty smooth for me because I was on my game. Because it was my first hit and I was yet to get into the groove, we had some pretty tough rallies," China's Lin, who faces a potential match-up with old rival Taufik Hidayat in the last 16, told Reuters.

"You know it's the Olympics and even though it's just the first round you can still lose, so I was hoping I could play well."

China's all-powerful team swept all five of the world titles at the same venue last year and are primed to achieve the same feat at London, but Danish veteran Peter Gade kept the flag flying for Europe with a 21-14 21-8 win over Portugal's Pedro Martins.

The 35-year-old Dane put on a regal performance, and received a royal hug from a very casually-dressed crown prince Frederik of Denmark after the match.

"Yeah, it was nice," said world number five Gade, who has been dealing with an ankle injury in the leadup, among a litany of aches and pains over a long and storied career.

"He just told me well done and congratulated me for getting through. He loves his badminton and has come to a few of my games."

Other players were much happier to fly below the radar, including Saina Nehwal who thrashed Belgium's Lianne Tan to quietly stroll into the last 16 of the women's singles.

Nehwal, India's greatest hope of a maiden badminton gold, said she had been avoiding reading news reports at home for fear of feeling enormous expectations there.

"I just want to be quiet, just focused on my matches. Of course India's a country where you get a lot of support and a lot of media attention.

"It's too much pressure because they are big games. And if you win your first round, it's like you've won the gold medal."

China's top women all proceeded smoothly, with world number one Wang Yihan easing past Canada's Michele Li 21-8 21-16. She was joined in the last 16 by second-seeded countrywoman Wang Xin who blasted American Rena Wang 21-8 21-6.

Day four sees Indonesia's Hidayat, who won gold at the 2004 Athens Games, bid to sew up a last 16 spot and a crunch match against Lin.